A total of 348 cases have been reported in travellers returning from Nigeria so far this year, with a further 170 cases in those returning from Ghana.

Dr Jane Jones, a travel health expert at the HPA, said: "All travellers to malaria risk areas - whether native to that country or not - need to be aware of the risk when travelling.

"Pre-travel medical advice should be sought from a GP or a travel clinic at least six weeks before travel and travellers must take medication before, during and after their trip, as well as anti-mosquito precautions while they are away, to keep safe."